Many chemical reaction vessels are equipped with agitation means for various reasons. Agitation is required in the suspension process for making polyvinyl chloride in order to keep the monomer in a dispersed state and also to assist in the cooling of this exothermic reaction. The amount and type of agitation can greatly change the properties of the polymer obtained from the reaction vessel. Agitation must frequently be changed if the desired properties of the product are changed.
Agitation in a chemical reaction vessel is normally achieved by a plurality of agitation blades permanantly attached to a hub which is attached to a shaft extending into the reaction vessel. These blades can vary in number, size and shape. Some are curved, some are at an angle, some are straight and flat. When a different form of agitation is required, the hub is removed from the shaft and another hub is bolted to the shaft. The new hub having a different set of agitator blades permanantly attached thereto.
This prior process requires a large number of different blade-hub combinations to cover a broad range of agitation requirements. It would be desirable to have a blade-hub combination that could be used for different agitation requirements. The present invention overcomes these objections by providing an agitation blade and hub assembly that permits adjustment of the blade in pitch as well as replacement of blade size in a minimum of down time.